An apparatus for changing rotation direction of pedal shaft for a bicycle, capable of traveling forward the bicycle when pedaling the bicycle forward or rearward, has been disclosed. In particular, typical examples thereof are disclosed by Mantzoursos et al. and Foster.
According to the invention of Mantzoursos et al. (EPO Publication No. 0 369 925, published on May 23, 1990), two gears having a one way mechanism are fixed to pedal shaft and a drive switching gear is installed between above two gears, which is detachable.
Thus, when the drive switching gear is engaged with above two gears, whether the axis of pedals is rotated forward or rearward, a sprocket wheel rotates forward.
According to the invention of Foster (U.S. Pat. No. 5,435,583), a gear box is installed on a pedal shaft, in which two gears, a clutch assembly located on a shaft between two gears, and a bevel gear which is placed between both two gears are installed. Here, the bicycle of this invention can travel like a general bicycle by pedaling with the clutch disk is coupled with the right gear. However, when pedaling rearward with the clutch disk is coupled with the left gear, the rotation direction is changed by the bevel gear, so that the bicycle travels forward.
The above two inventions are meaningful in the aspect of the bi-directional pedaling apparatus which can drive the bicycle forward when pedaling rearward by adopting a drive switching portion. However, the life span of the bi-directional pedaling apparatus becomes short due to abrasion of a specific portion on which a force required for changing the power direction is concentrated.
By making up such weak points, the present inventor has disclosed an apparatus for changing power direction for a bicycle in the Korean Patent Publication No. 97-42078(PCT Publication No. WO 97/21587, published on Jun. 19, 1997).
According to the apparatus for changing power direction for a bicycle, a shaft housing, which supports a pedal shaft, has an opening portion, and first pawls are installed along inner circumference of the opening portion, a changing ring has holes along the circumference and has a inner gear, a carrier has planetary gears, inner ratchet teeth, and outer ratchet teeth, a sun gear, which is fixed to the pedal shaft, has second pawls engaged with the inner ratchet teeth, is engaged with the planetary gears, a sprocket cap has inner gear portion, which is engaged with the planetary gears, and a first gear which is engaged with the inner gear of the changing ring, rotates the changing ring with predetermined angle, so that control the first pawls.
In the state of the first pawls are not engaged with outer ratchet teeth of the carrier, the apparatus can travel a bicycle forward by pedaling forward, and idle the bicycle by pedaling rearward like a conventional bicycle.
When the pedal shaft rotates forward in this state, the sun gear rotates forward which is fixed to the pedal shaft, then the second pawls of the sun gear is engaged with the inner ratchet teeth, the carrier rotates. And the planetary gears of the carrier are engaged with inner gear portion of the sprocket cap, then, the sprocket rotates forward. Therefore, the rear wheel of the bicycle rotates forward.
In the other hand, when the pedal shaft rotates rearward in this state, the second pawls are not engaged with the inner ratchet teeth of the carrier, then, the pedal is idled.
In the state of the first pawls are engaged with outer ratchet teeth of the carrier, the apparatus can travel a bicycle forward whether pedaling forward or rearward.
In this state, when the pedal shaft rotates forward, the rear wheel of the bicycle rotates forward the same operation of the first pawls are not engaged case.
In the other hand, when the pedal shaft rotates rearward in this state, the carrier is fixed to shaft housing because the outer ratchet teeth of the carrier is engaged with the first pawls, the planetary gears of the carrier rotates the inner gear portion of the sprochet cap, then the rear wheel of the bicycle forward.
But, the bicycle is pulled rearward in this state, the rearward driving force of the sprocket, to which connected to the sprocket cap, is to rotate the planetary gears, and the planetary gears drive the sun gear forward, then the pedal shaft rotates rearward.
As a result, there is no function that the bicycle can be pulled rearward without a load in that apparatus.